The timing of the injury may see Mooy left out completely from the Asian Cup squad rather than Graham Arnold bank on the 28 year old regaining fitness in time for the knockout stages - should Australia get that far.

Mooy has been the heartbeat of the Socceroos side for a number of years now with his set-pieces a key part of Australia's game.

While his performances of late for the national had left something to be desired, Mooy's consistent presence in midfield will take some replacing.

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In more bads news for the Socceroos, Tom Rogic is also under an injury cloud with a knee injury, though it doesn't appear to be as bad as Mooy's injury.

Australia will already be without teenage sensation Daniel Arzani, who has been ruled out for the season after suffering an ACL injury in his Celtic debut.

The Socceroos Asian Cup squad is expected to be announced on December 19 with Arnold now left to deal with another major headache.